Melting and crystallization in Ni nanoclusters: The mesoscale regime

We studied melting and freezing of Ni nanoclusters with up to 8007 atoms ~5.7 nm! using molecular dynamics with the quantum-Sutten‐Chen many-body force field. We find a transition from cluster or molecular behavior below ;500 atoms to a mesoscale nanocrystal regime ~well-defined bulk and surface properties! above ;750 atoms ~2.7 nm!. We find that the mesoscale nanocrystals melt via surface processes, leading to Tm,N5Tm,bulk2aN 21/3 , dropping from Tm,bulk51760 K to Tm,336 5980 K. Cooling from the melt leads first to supercooled clusters with icosahedral local structure. For N.400 the supercooled clusters transform to FCC grains, but smaller values of N lead to a glassy structure with substantial icosahedral character. © 2001 American Institute of Physics. @DOI: 10.1063/1.1373664#

[1]  Saroj K. Nayak,et al.  Thermodynamics of small nickel clusters , 1998 .

[2]  J. Cohen,et al.  Melting of Pb nanocrystals , 1998 .

[3]  B. K. Rao,et al.  Science and Technology of Atomically Engineered Materials , 1996 .

[4]  Hall,et al.  Multiply twinned structures in unsupported ultrafine silver particles observed by electron diffraction. , 1991, Physical review. B, Condensed matter.

[5]  R. Whetten,et al.  Statistical thermodynamics of the cluster solid-liquid transition. , 1990, Physical review letters.

[6]  William A. Goddard,et al.  Molecular-dynamics simulations of glass formation and crystallization in binary liquid metals: Cu-Ag and Cu-Ni , 1999 .

[7]  J. Farges,et al.  Comparison between icosahedral, decahedral and crystalline Lennard-Jones models containing 500 to 6000 atoms , 1989 .

[8]  Canada.,et al.  Melting, freezing, and coalescence of gold nanoclusters , 1997, cond-mat/9703153.

[9]  W. Goddard,et al.  Strain Rate Induced Amorphization in Metallic Nanowires , 1999 .

[10]  H. C. Andersen,et al.  Icosahedral ordering in the Lennard-Jones liquid and glass. , 1988, Physical review letters.

[11]  S. A. Cho,et al.  Role of lattice structure on the Lindemann fusion theory of metals , 1982 .

[12]  Rustum Roy,et al.  Materials Research Society , 1984 .

[13]  J. P. Perez,et al.  FROM FREE CLUSTERS TO CLUSTER-ASSEMBLED MATERIALS , 1995 .

[14]  Shozo Ino,et al.  Stability of Multiply Twinned Particles , 1969 .

[15]  U. Landman,et al.  The energetics and structure of nickel clusters: Size dependence , 1991 .

[16]  R. Vanselow.  Chemistry and physics of solid surfaces VII , 1988 .

[17]  Fuchs,et al.  Numerical evidence of an embryonic orientational phase transition in small nitrogen clusters. , 1996, Physical Review Letters.

[18]  Schafer,et al.  Melting of isolated tin nanoparticles , 2000, Physical review letters.

[19]  A. Mackay.  A dense non-crystallographic packing of equal spheres , 1962 .

[20]  M. Manninen,et al.  Melting of copper clusters , 1993 .

[21]  W. Goddard,et al.  Calculation of Mechanical, Thermodynamic and Transport Properties of Metallic Glass Formers , 1998 .

[22]  Lai,et al.  Size-Dependent Melting Properties of Small Tin Particles: Nanocalorimetric Measurements. , 1996, Physical review letters.

[23]  David Turnbull,et al.  Kinetics of Heterogeneous Nucleation , 1950 .

[24]  J. Jellinek,et al.  Surface melting in Ni55 , 1993 .

[25]  Hellmut Haberland.  Theory, experiment, and clusters of atoms , 1995 .

[26]  Mostafa A. El-Sayed,et al.  Shape Transformation and Surface Melting of Cubic and Tetrahedral Platinum Nanocrystals , 1998 .

[27]  U. Landman,et al.  Melting of gold clusters , 1999 .

[28]  P. Buffat,et al.  Size effect on the melting temperature of gold particles , 1976 .

[29]  H. Haberland,et al.  Experimental Determination of the Melting Point and Heat Capacity for a Free Cluster of 139 Sodium Atoms , 1997 .

[30]  Yu,et al.  Kinetics of nonequilibrium shape change in gold clusters. , 1995, Physical review. B, Condensed matter.

[31]  W. Poschenrieder,et al.  Observation of clusters in a sputtering ion source , 1973 .

[32]  H. Haberland.  Clusters of atoms and molecules : theory, experiment, and clusters of atoms , 1994 .

[33]  Andreoni,et al.  Melting of small gold particles: Mechanism and size effects. , 1991, Physical review letters.

[34]  M. Baker,et al.  Charge transfer in thunderstorms and the surface melting of ice , 1989 .